This fancy ichneumonid wasp wandered a little on the window frame, a female Tromatobia lineatoria ^[1] (validation determination). A new garden species.

This species lays her eggs in spider egg sacks ^[2].

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References

¹ Nederlands Soortenregister

² FITTON, Michael Geoffrey, et al. Pimpline ichneumon-flies. Hymenoptera, Ichneumonidae (Pimplinae). Pimpline ichneumon-flies. Hymenoptera, Ichneumonidae (Pimplinae)., 1988, 7.1.